Concrete structures must maintain their shielding abilities and structural integrity over extended operational periods. Despite the widespread use of dry storage systems for spent nuclear fuel, research on the properties of deteriorated concrete and their impact on structural performance remains limited. To address this significant research gap, static and dynamic material testing was conducted on concrete specimens carefully extracted from the outer wall of the High-flux Advanced Neutron Application ReactOr (HANARO), constructed approximately 30 years ago. Despite its age, the results reveal that the concrete maintains its structural integrity impressively well, with static compression tests indicating an average compressive strength exceeding the original design standards. Further dynamic property testing using advanced high-speed material test equipment supported these findings, showing the consistency of dynamic increase factors with those reported in previous studies. These results highlight the importance of monitoring and assessing concrete structures in nuclear facilities for long-term safety and reliability.

It was found in this study that fluorinated microporous carbon aerogels with enhanced hydrophobicity could be successfully prepared by direct fluorination to separate water-in-oil emulsions at high flux. The fluorinated carbon aerogel (F-CA) surface treated by the fluorination method had a water contact angle of 151.2° and could immediately absorb oil. In addition, the unique network structure of F-CA and its hydrophobicity allow surfactant-stabilized water-in-oil emulsions to be effectively and simply separated under gravity without requiring external forces such as vacuum or pressurization. The network structure of F-CAs consists of randomly connected spherical particles that form fluorinated permeation channels, which induce high flux during emulsion separation. The F-CA spherical particles have nanosized pores and high hydrophobicity, which repel and trap water droplets to increase the separation purity. Therefore, F-CA exhibited excellent performance, such as high filtrate purity (up to 99.9954%) and flux (up to 11,710 L/m2h). Furthermore, F-CA reusability was demonstrated as it did not lose its hydrophobicity and maintained its performance even after repeated use. This type of aerogel has great potential to be utilized throughout various environmental fields, including oil remediation.

Ecosystems provide various ecosystem services based on biodiversity. However, biodiversity is facing crises due to anthropogenic factors such as pollution, land use change, and climate change. Threats to biodiversity can significantly impact the provision and stability of ecosystem services, extending beyond simple species decline. To address threats to biodiversity, it is crucial to evaluate how anthropogenic factors affect not only biodiversity but also ecosystem services. This study aims to investigate the energy flux in a post-mining area based on the biodiversity of soil ecosystems and assess its suitability as an evaluation metric. It was observed that as the concentration of the primary pollutant, arsenic, increased, both the biomass of soil organisms and energy flux decreased. Furthermore, soil ecosystem multifunctionality may be negatively affected by pollution. These findings contribute to understanding the impact of pollution on soil ecosystem biodiversity and energy flux in post-mining areas and provide important information for more effective conservation and management of ecosystem services.

본 연구에서는 고투과성 및 높은 염 제거율을 가지는 역삼투막의 성능향상을 위하여 다양한 첨가제 및 계면중합 시 경화 온도 및 시간에 따른 특성평가에 대한 연구가 수행되었다. 첨가제가 없는 막과 첨가제를 첨가한 막의 모폴로지는 모 두 “ridge-and-valley” 구조를 나타내어, 폴리아미드 층이 다공성 지지층 표면에 성공적으로 중합되었음을 확인하였다. 또한 2-Ethyl-1,3-hexanediol (EHD) 첨가함으로써 향상된 친수성과 수투과율 가졌으며, 이는 접촉각 측정을 통해서 확인되었다. 최 종적으로 97.78%와 98.7%의 NaCl 및 MgSO4 제거율과 3.31 L/(m2⋅h⋅bar)의 높은 수투과율을 가진 고투과성 계면중합막을 제조하였다.

Nowadays, transferred type arc plasma torches have been widely present in industrial applications, in particular, using melting pool of electrically conducting materials such as arc furnace, welding and volume reduction of radioactive wastes. In these applications, the melting pools are normally employed as an anode, thus, heat flux distributions on anode melting pool need to be characterized for optimum design of melting pool system. For this purpose, we revisited the one-dimensional model of the anode boundary layer of arcs and solved governing equations numerically by using Runge-Kutta method. In addition, the direct melting process of non-combustible wastes in the crucibles were discussed with the calculation results.

본 연구에서는 투과 유량 모델을 개발하기 위하여, 시간, 막 전후의 압력 차, 회전 속도, 막의 기공 크기, 동점도, 농도 및 공급 유체의 밀도 등 7개의 입력 변수에 기반한 두 종류(ANN 및 SVM) 인공지능 기법을 이용하였다. 시행착오법과 실험데이터와 예측 데이터 간의 결정 계수(R2) 와 평균절대상대편차(AARD)를 포함한 두 가지 통계 변수를 통해 최적의 모델 을 선정하였다. 최종적으로 얻어진 결과에서 최적화된 ANN 모델이 R2 = 0.999 및 AARD% = 2.245인 투과 플럭스 예측 정 확도를 보여서, R2 = 0.996 및 AARD% = 4.09의 정확도를 보인 SVM 모델에 비해 더 정확함을 알 수 있었다. 또한, ANN 모델은 SVM 방식에 비해 투과 유속을 예측하는 능력도 더 높은 것으로 나타났다.

본 논문은 슬로싱 상태에 놓인 포화 상태 액체수소탱크에서 열 유속 및 BOG(Boil-off gas)의 경향을 다루고 있다. 특히, 액체-기체 간의 침투 및 혼합에 의한 열 교환에 관심을 두었다. 먼저, VOF(Volume of fluid)와 Eulerian 기반의 다상 유동모델로 모형 슬로싱 실험 을 모사하여 압력을 예측하고 계측된 값과 비교하였다. 자유 수면 및 충격 압력 실험 결과와 해석 결과를 비교하였으며, 유체의 속도 예측에서 정확할 수 있음을 간접적으로 증명하였다. 그리고 2차원의 Type-C 원통형 수소탱크를 대상으로 다상열유동해석을 수행하 였다. 이때 포화상태에 놓인 액체 및 기체수소를 가정하고, 해석을 통해 각 상간의 혼합에 의한 열 교환의 수준을 확인하고자 하였다. 단, 상간의 열 교환만을 관심으로 두고 있었으므로 질량전달 및 기화모델은 해석에서 제외하였다. 최종적으로 상의 혼합으로 인해 액 체수소로 유입되는 열 유속의 기여도에 대하여 정리하였다. 또한 액체수소로 유입되는 열 유속과 집중 질량 기반의 간이식을 통해 BOG 발생량 및 경향을 예측하고 분석하였다.

In the flux used in the batch galvanizing process, the effect of the component ratio of NH₄Cl to ZnCl₂ on the microstructure, coating adhesion, and corrosion resistance of Zn-Mg-Al ternary alloy-coated steel is evaluated. Many defects such as cracks and bare spots are formed inside the Zn-Mg-Al coating layer during treatment with the flux composition generally used for Zn coating. Deterioration of the coating property is due to the formation of AlClx mixture generated by the reaction of Al element and chloride in the flux. The coatability of the Zn-Mg-Al alloy coating is improved by increasing the content of ZnCl2 in the flux to reduce the amount of chlorine reacting with Al while maintaining the flux effect and the coating adhesion is improved as the component ratio of NH4Cl to ZnCl2 decreases. Zn-Mg-Al alloy-coated steel products treated with the optimized flux composition of NH₄Cl•3ZnCl₂ show superior corrosion resistance compared to Zn-coated steel products, even with a coating weight of 60 %.

Forward osmosis (FO) process is a chemical potential driven process, where highly concentrated draw solution (DS) is used to take water through semi-permeable membrane from feed solution (FS) with lower concentration. Recently, commercial FO membrane modules have been developed so that full-scale FO process can be applied to seawater desalination or water reuse. In order to design a real-scale FO plant, the performance prediction of FO membrane modules installed in the plant is essential. Especially, the flux prediction is the most important task because the amount of diluted draw solution and concentrate solution flowing out of FO modules can be expected from the flux. Through a previous study, a theoretical based FO module model to predict flux was developed. However it needs an intensive numerical calculation work and a fitting process to reflect a complex module geometry. The idea of this work is to introduce deep learning to predict flux of FO membrane modules using 116 experimental data set, which include six input variables (flow rate, pressure, and ion concentration of DS and FS) and one output variable (flux). The procedure of optimizing a deep learning model to minimize prediction error and overfitting problem was developed and tested. The optimized deep learning model (error of 3.87%) was found to predict flux better than the theoretical based FO module model (error of 10.13%) in the data set which were not used in machine learning.

시설 토양 오이재배에서 토양수분장력계를 이용하여 관수 제어하였을 때 오이의 광합성 형광반응, 수액 흐름, 엽온 등에 미치는 영향을 구명하고자 실험을 수행하였다. 오이(Cucumis sativus L.)‘청춘’(해오름 종묘)을 공시하여 관수개시점 10-10-20kPa 또는 20-10-10kPa의 2처리하였다. 766 ~ 854 W·m -2 의 고광, 32°C 이상의 고온인 처리 66일 째 광합성형광반응변수(Fo, Fm, Fv/Fm)값은 처리 간 차이가 컸다. 66일 째 낮 시간 (오전 10시 반 ~ 오후 6시)의 Fo와 Fv/Fm값은 10-10-20kPa 처리보다 20-10-10kPa 처리에서 높았다. 엽온이 높았을 때 Fv/Fm값은 감소하였다. 28일과 66일째 엽생육(엽장, 엽폭, 엽면적)은 차이가 없었으나 엽록소 함량(SPAD 값)은 20-10- 10kPa 처리에서 유의하게 높았다. 광도와 온도가 증가함에 따라 줄기수액흐름상대율(SFRR)과 엽온은 상승하였다. 두 처리구 모두 SFRR은 광도 170 W·m -2 이상인 오전 8시 ~ 9시 간대에 급격한 증가가 시작되었다. 관수 후의 처리구 토양 온도는 감소하였으나, 7월 5일(광도 820W·m -2 , 오후 1시) 토양 온도가 10-10-20kPa에서는 31.0°C, 20-10-10kPa에서는 28.5°C였다. 그러나 처리 간 SFRR, 엽온, 기온차, VPD는 차이가 없었다. SFRR과 엽온 간에는 정의 상관성(p < 0.01, r = 0.770)을 보였으며, SFRR과 엽온은 광, 온도, 토양 온도, 토양 수분함량, VPD 간에는 정의 상관을 상대습도와 기온차 간에는 부의 상관을 보였다.

This paper reports critical heat flux(CHF) performance on wire heater according to material, thickness, length, cross sectional shape. Water was employed as the working fluid, which was saturated at 1 atm. By comparison of CHF values with difference conditions of wire length, contact resistance inherent in the experimental apparatus could be analyzed, which had made the bias error in many research groups. So, exact value of CHF could be measured, which was consistent with the literatures. The CHF value showed decrease tendency, as the cross sectional area increased and reach to the capillary length of the working fluid. Meanwhile, the effect of thermal properties on CHF was not observed in the experimental cases. This data would be used as a reference data in research field of CHF using wire heater, i.e. reactivity initiative accident(RIA).